This book offers a valuable contribution to the field of minimally invasive coronary intervention, presenting the latest developments in slender catheters, their development and the related research findings. With the growing interest in trans-radial interventions (TRIs) and distal radial approach, "Slender PCI" has been popular in Japan. Although "Slender PCI" started with using a small diameter catheter of a 5Fr Guiding Catheter, recently it becomes a generic term for all minimally invasive catheter Interventions. "Slender PCI" not only makes less painful but also reduces exposure to radiation and contrast agents. In addition, the book highlights the distal radial approach, 5Fr guiding catheter for treating complex lesion, 4Fr guiding catheters, 3Fr diagnosis catheters. The authors share their experiences and know-how throughout, providing abundant illustrations to enhance readers’ understanding.